For a driving apparatus used for an image forming apparatus such as a printer, a copying machine, a fax machine, a multi-functional machine, etc., a driving apparatus provided with various driving mechanisms for transmitting driving force to a rotor via a gear has been proposed to date.
For example, Patent document 1 discloses a driving mechanism for a photoreceptor drum as follows. In a tandem-type image forming apparatus having four photoreceptor drums yellow, magenta, cyan, and black, referred to respectively as Y, M, C, and K, the photoreceptor drum K is rotationally driven by a drive motor for the photoreceptor drum K, while the photoreceptor drums Y, M, and C are rotationally driven by a color drive motor. The photoreceptor drums Y, M, and C are respectively provided coaxially with a photoreceptor gear; with a gear connected to a rotational axis of the drive motor, driving force is transmitted directly to the photoreceptor gear of the photoreceptor drums Y and M, and is transmitted from the photoreceptor gear of the photoreceptor drum M via an idler gear to the photoreceptor gear of the photoreceptor drum C.
Moreover, Patent document 2 discloses a driving mechanism for a paper-feeding apparatus as follows. In the paper-feeding apparatus used for an image forming apparatus, a paper-feeding roller is rotationally moved around an arm axis of an arm member (a supporting point) so as to be moved, which paper-feeding roller is provided at a tip of the arm member which is supported rotatably according to the height of a loading face of a sheet to be sent out in order to ensure sending out the sheet loaded on a sheet containing unit. Here, rotational driving force of the paper-feeding roller is transmitted from a driving gear coaxially provided with the arm axis onto the arm via multiple idler gears which are respectively provided with rotational axes.
Moreover, representative examples of a driving mechanism which rotationally drives multiple rotors using one drive motor and moves at least one rotor includes what is used in a fixing apparatus for use in an image forming apparatus. A fixing apparatus which includes a fixing roller which is a rotor such that the axial center of the rotor that is rotationally driven by the drive motor does not move, and a pressurizing roller which is a rotor such that the axial center of the rotor moves has been used to date. Here, the object of movably providing the pressurizing roller is to adjust the pressure at which the sheet is held, and a width of a nip portion formed by the fixing roller and the pressurizing roller depending on the type (double sided/single sided, monochrome/full color, etc.) of image formation for forming on a sheet to be fixed onto, the type of the sheet, thickness, etc. In the driving mechanism of the fixing apparatus as described above, it has been common to transmit rotational driving force to the driving gear provided at the pressurizing roller via multiple idler gears and a driving gear provided at the fixing roller.